IR and Raman studies of polythiophene prepared by electrochemical polymerization

IR and Raman studies have been carried out for polythiophene prepared by electrochemical polymerization and subsequently treated with aq. NH₄OH solution to neutral film. Four additional strong absorption bands at 1330, 1200, 1100 and 1030 cm^?1 appeared upon doping irrespective of the nature of dopants and their intensities increased with increasing dopant concentration. Polydeuterothiophene obtained by the same method gave similar additional strong bands shifting slightly to lower frequencies. These four intense IR bands did not appear in the Raman spectra of doped polythiophene films. Origin of these IR bands can be attributed to ring stretching of the charged polythiophene chain.